This invention relates to coupling a power line communications signal in both directions between two three-phase power lines, wherein the signaling mode is phase-to-neutral on one of the power lines and phase-to-phase on the other.
Power line communications signals are transmitted on three-phase lines alternatively in a phase-to-neutral mode and in a phase-to-phase mode. It is sometimes important to couple between power lines that are using these opposite modes. It is believed that none of the prior art coupling circuits can provide an optimized bilateral coupling between a wye feeder with a balanced phase-to-neutral signal and a delta feeder with opposing phase-to-phase signals. The present invention provides such a coupling circuit. It is a circuit using only passive components and is particularly applicable to communication signals having a carrier frequency in the 3-10 KHz range.